This application is based upon and claims the benefit of priority from the prior Japanese Patent Application PH2001-055847, filed on Feb. 28, 2001; the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a route guidance apparatus and a method for executing route guidance for a pedestrian by presenting a route guidance sentence or a simplified map.
2. Background of the Invention
Recently, a route guidance apparatus for presenting a route guidance sentence and a simplified map to a destination for a pedestrian is developed. This route guidance apparatus is a simple portable device or is loaded to a portable communication terminal such as a cellular-phone or a personal data assistant (PDA).
A route guidance technique using the route guidance sentence and the simplified map is disclosed in the following two references.
(1) TECHNICAL REPORT OF IEICE, PRU95-215(1996-02), xe2x80x9cInteractive Generation of a Route and Its Application to Generating a Sketch Map Drawing in a Map Image Information Systemxe2x80x9d Masahiko HORIE, Toshihiro KIMURA, Noboru BABAGUCHI, Seiichiro DAN and Tadahiro KITAHASHI
(2) TECHNICAL REPORT OF IEICE, PRMU96-156(1997-01), xe2x80x9cModeling of Geographic Road Structure for Generation of Sketch Map Image and Linguistic Guidexe2x80x9d Toshihiro KIMURA, Yoshihiro SUZUKI, Seiichiro DAN, Noboru BABAGUCHI and Tadahiro KITAHASHI
As for generation of the route guidance sentence, in reference (1), for example, a sentence xe2x80x9cPlease go forward to the west direction by 20 meters.xe2x80x9d or xe2x80x9cPlease turn to the right at the junction.xe2x80x9d, can be presented. However, especially, numerical value representing distance such as xe2x80x9c** metersxe2x80x9d is difficult for a pedestrian to apply. Furthermore, innumerable junctions exist in a town area, and the pedestrian often mistakes a junction indicated by the route guidance sentence for another junction. Accordingly, such route guidance sentence is not always easy for the pedestrian to sufficiently understand.
In reference (2), for example, a route guidance sentence such as xe2x80x9cThis road joins another road.xe2x80x9d or xe2x80x9cYou advance to ** at a crossroads.xe2x80x9d, is only presented. This route guidance sentence is more difficult for the pedestrian to understand than the route guidance sentence disclosed in the reference (1).
Furthermore, in the reference (2), generation of a simplified map for guidance using a signpost for pedestrian (i.e., a landmark) is disclosed. However, generation of a route guidance sentence using the landmark is not disclosed in the references (1) or (2). In the reference (2), the target object is reserved. As for other landmarks, the landmark far from a main junction is removed in order to simply present the landmark. However, if this method is used for generation of the route guidance sentence, for example, a complicated route guidance sentence using many landmarks is generated at a place neighboring the main junction. Thus, easiness of the route guidance produces a contrary effect.
As mentioned-above, in the known route guidance technique, presentation of the route guidance sentence is not always easy for the pedestrian to understand, and it often happens that the pedestrian misunderstands a junction point, a joint point, or a divergence point indicated by the route guidance sentence.
Furthermore, a method for effectively utilizing landmarks for generation of the route guidance sentence is not found. In short, it is impossible to execute easy route guidance for the pedestrian by using landmarks.
It is an object of the present invention to provide a route guidance apparatus and a method to present route guidance easy for the pedestrian to understand.
According to the present invention, there is provided a pedestrian route guidance apparatus, comprising: a database configured to store map data including road network data and landmark data; a A route search unit configured to search for a route from a departure point to a destination point from the road network data stored in said database; a road pattern analysis unit configured to analyze a route pattern of the route by referring to the road network data, and to obtain road pattern data as the analysis result; a landmark selection area decision unit configured to determine a landmark selection area for route guidance along the route based on the road network data and the road pattern data; a landmark selection unit configured to select landmark data included in the landmark selection area from said database; a route guidance information generation unit configured to generate route guidance information of the route using the road pattern data and the landmark data selected by said landmark selection unit; and a presentation unit configured to present the route guidance information.
Further in accordance with the present invention, there is also provided a pedestrian route guidance method, comprising: storing map data including road network data and landmark data in a database; searching for a route from a departure point to a destination point from the road network data stored in the database; analyzing a route pattern of the route by referring to the road network data; obtaining road pattern data as the analysis result; determining a landmark selection area for route guidance along the route based on the road network data and the road pattern data; selecting landmark data included in the landmark selection area from the database; generating route guidance information of the route using the road pattern data and the selected landmark data; and presenting the route guidance information.
Further in accordance with the present invention, there is also provided a computer program product, comprising: a computer readable program code embodied in said product for causing a computer to execute pedestrian route guidance, said computer readable program code having: a first program code to store map data including road network data and landmark data in a database; a second program code to search for a route from a departure point to a destination point from the road network data stored in the database; a third program code to analyze a route pattern of the route by referring to the road network data; a fourth program code to obtain road pattern data as the analysis result; a fifth program code to determine a landmark selection area for route guidance along the route based on the road network data and the road pattern data; a sixth program code to select landmark data included in the landmark selection area from the database; a seventh program code to generate route guidance information of the route using the road pattern data and the selected landmark data; and a eighth program code to present the route guidance information.